Treatment of preeclampsia and preterm labor with combination of progestational agent and a nitric oxide synthase substrate and/or donor

ABSTRACT

Preeclampsia and preterm labor in a pregnant female mammal are treated by administering thereto a combination of a progestin and a nitric oxide synthase substrate, a nitric oxide donor or both, optionally in further combination with one or more of a cyclooxygenase inhibitor, a PGI 2  -mimetic, a thromboxane (TXA 2 ) inhibitor, a compound possessing TXA 2  -agonistic and TXA 2  -inhibiting properties, a compound possessing TXA 2  -antagonistic and PGI 2  -memetic activities, and a TXA 2  antagonist.

BACKGROUND OF THE INVENTION

This invention relates to a method for the treatment of preeclampsia andof preterm labor with the combination of a progestational agent and anitric oxide synthase substrate, a nitric oxide donor or both, alone orin further combination with one or more of a cyclooxygenase inhibitor, aPGI₂ -mimetic, a thromboxane (TXA₂) inhibitor, A compound possessingTXA₂ -agonistic and TXA₂ -inhibiting properties, a compound possessingTXA₂ antagonistic and PGI₂ -memetic activities, and a TXA₂ antagonist,and to pharmaceutical compositions comprising such a combination.

Preeclampsia, toxemia or eclampsia of pregnancy can be a significanthealth problem during pregnancy and they are the leading causes of fetalgrowth retardation, fetal mortality and morbidity, premature birth andmaternal mortality. The etiology of the disease is largely unknown andeffective therapy is not available. Preeclampsia of pregnancy ischaracterized by a triad of hypertension, pathological edema andproteinuria. This disease affects 6 to 10% of all pregnancies.

Recently, nitric oxide has been shown to be endothelium derived relaxingfactor (EDRF) from the endothelium of blood vessels. Nitric oxide isconsidered to be a major mediator in the control of vascular reactivity.Nitric oxide is synthesized from L-arginine by nitric oxide synthaselocated in endothelial cells. Nitric Oxide can also be generated byapplication of various nitric oxide donors such as sodium nitroprusside,nitroglycerin, glyceryl trinitrite, SIN-1, isosorbid mononitrite,isosorbid dinitrite, etc.

Treatment of pregnant rats with nitric oxide synthase inhibitors, whichare analogues of L-arginine (such as L-NAME, N^(G) -nitro-L-argininemethyl ester) results in elevated blood pressure, fetal retarded growthand proteinuria. Thus, inhibition of nitric oxide synthesis producesconditions and symptoms identical to preeclampsia of pregnancy andestablishes that preeclampsia is the direct result of the decrease innitric oxide synthesis and/or a change in the regulation of vasculartone. These conditions give rise to increased blood pressure, decreasedblood flow to the fetus, retarded fetal development and proteinuria.Agents which raise nitric oxide levels therefore are useful in thetreatment of preeclampsia of pregnancy. Since nitric oxide donors alsoreduce contractility of the uterus during pregnancy, nitric oxide donorsare also useful for use in preterm labor.

The nitric oxide effects on smooth muscle depend upon the activation ofguanylate cyclase and generation of cGMP to produce relaxation and thisstep is progesterone dependent. Thus, combinations of nitric oxidedonors with progesterone are particularly efficacious for the treatmentof preeclampsia and of preterm labor.

EP 0 441 119 A2 discloses the use of L-arginine in the treatment ofhypertension and other vascular disorders. It suggests that themechanism by which L-arginine is effective for this purpose is becauseit may be the physiological precursor of "the most powerfulendothelial-derived releasing factor, nitric oxide." The use ofL-arginine in combination with other pharmaceutically active agents isnot discussed in this publication.

OBJECTS OF THE INVENTION

It is an object of the invention to provide a method for the preventionand treatment of preeclampsia with a combination of a progestationalagent and a nitric oxide substrate and/or donor.

It is another object to provide such a method in which a progestationalagent is used in combination with a nitric oxide substrate and/or donorfor the prevention and treatment of preeclampsia.

It is a further object to provide a method for the prevention andtreatment of preterm labor using a progestational agent in combinationwith a nitric oxide substrate and/or donor.

A further object is the provision of pharmaceutical compositions usefulin practicing the methods of this invention.

Other objects will be apparent to those skilled in the art to which thisinvention pertains.

SUMMARY OF THE INVENTION

In a method aspect, this invention relates to a method of treating atleast one of preeclampsia and preterm labor in a pregnant female whichcomprises administering to a pregnant female manifesting the symptomsthereof, (a) a progestational agent and (b) one or both of a nitricoxide synthase substrate and a nitric oxide donor, alone or in furthercombination with one or more of a cyclooxygenase inhibitor, a PGI₂-mimetic, a thromboxane (TXA₂) inhibitor, a compound possessing TXA₂-agonistic and TXA₂ -inhibiting properties, a compound possessing TXA₂-antagonistic and PG1₂ -memetic activities, and a TXA₂ antagonist, inamounts effective to ameliorate the symptoms thereof, the amount of theprogestational agent administered being bioequivalent to 50-300 mg. ofinjected progesterone and the amount of the nitric oxide synthasesubstrate, nitric oxide donor or both being effective to, respectively,either raise the blood level of circulating L-arginine in a pregnantfemale to whom the composition is administered to at least about 1 mmoleabove the normally 2 to 3 mmolar circulating levels or raise nitricoxide donor levels to about 1 to 100 nmolar (nanamolar).

In another method aspect, this invention relates to a method of treatingpreterm labor in a pregnant female which comprises administering to apregnant female manifesting the symptoms thereof, amounts of (a) aprogestational agent and (b) at least one of a nitric oxide synthasesubstrate and a nitric oxide donor effective to terminate the pretermlabor, alone or in further combination with one or more of acyclooxygenase inhibitor, a PGI₂ -mimetic, a thromboxane (TXA₂)inhibitor, a compound possessing TXA₂ -agonistic and TXA₂ -inhibitingproperties, a compound possessing TXA₂ -antagonistic and PGl₂ -memeticactivities, and a TXA₂ antagonist, the amount of the progestationalagent administered being bioequiva-lent to 50-300 mg. of injectedprogesterone and the amount of the nitric oxide synthase substrate,nitric oxide donor or both being effective to, respectively, eitherraise the blood level of circulating L-arginine in a pregnant female towhom the composition is administered to at least about 1 mmole above thenormally 2 to 3 mmolar circulating levels, or raise nitric oxide donorlevels to about 1 to 100 nmolar.

In a product aspect, this invention relates to a pharmaceuticalcomposition comprising (a) a progestational agent and (b) at least oneof a nitric oxide synthase substrate and a nitric oxide donor, alone orin further combination with one or more of a cyclooxygenase inhibitor, aPGI₂ -mimetic, a thromboxane (TXA₂) inhibitor, a compound possessingTXA₂ -agonistic and TXA₂ -inhibiting properties, a compound possessingTXA₂ -antagonistic and PGl₂ -memetic activities, and a TXA₂ antagonist,with the amount of the progestational agent per unit dosage beingbioequivalent to 50-300 mg. of injected progesterone and the amount ofthe nitric oxide synthase substrate, a nitric oxide donor or both perunit dosage being effective to, repsectively, either raise the bloodlevel of circulating L-arginine to at least about 1 mmole above thenormally 2 to 3 mmolar circulating levels or raise the nitric oxidedonor levels to about 1 to 1000 nmolar.

DETAILED DISCLOSURE

The methods of this invention treat one or more of preeclampsia andpreterm labor in a pregnant female mammal, preferably a human, who ismanifesting the symptoms thereof or who is a high risk candidate fordoing so, e.g., as determined by the progress of a present or previouspregnancy.

Because these abnormal conditions of pregnancy are produced by oraggravated by subnormal nitric oxide synthesis, both nitric oxidesynthase substrates, e.g., L-arginine, and nitric oxide donors, e.g.,sodium nitroprusside, nitroglycerin, glyceryl trinitrate, SIN-1,isosobid mononitrate and isosorbid dinitrate, are useful forameliorating the symptoms thereof and, in one aspect of the method ofthis invention, a combination of both are employed.

A synergistic effect is achieved when a progestational agent isadministered concurrently with the nitric oxide substrate and/or nitricacid donor.

Thus, the method aspect of this invention and the pharmaceuticalcomposition aspect of this invention employs a combination of (a) aprogestational agent, e.g., progesterone, and (b) either or both of anitric oxide donor and a nitric oxide synthase substrate and,optionally, (c) one or more of a cyclooxygenase inhibitor, e.g.,aspirin; a PGI₂ -mimetic, e.g., iloprost and cicaprost; a thromboxane(TXA₂) inhibitor, e.g., dazoxiben hydrochloride (benzoic acid, 4-2-(1H-imadazol1-yl)-ethoxy!-, monohydrochloride; UK 37248), dazmegrel(1H-indole-1-propanoic acid, 3-(1H-imidazol-1-ylmethyl)-2-methyl-; UK3885), ozagrel (2-propenoic acid, 3-4-(1-H-imidazol-1-ylmethyl)phenyl!-; OKY-046) and pirmagrel (imidazo1,5-a!pryidine-5-hexanoic acid; CGS-13080); a compound possessing TXA₂-agonistic and TXA₂ -inhibiting properties, e.g., ridogrel (pentanoicacid, 5- 3-pyri-dinyl 3-(trifluoromethyl)phenyl!methylene!-amino!oxy!-;R-68070) and labogrel (6-heptenoic acid, 7-phenyl-7-(3-pydridinyl)-; acompound possessing TXA -antagonistic and PGl₂ -memetic activities,e.g., 5-heptenoic acid, 7- 3- (diphenylmethoxy)-imino!-bicyclo,2.2.1!hept-2-yl!-; EP 035-rac) and 5-heptenoic acid, 7- 3-(diphenylmethoxy)-imino!methyl!biclo 2.2.2!-oct-5-en-2-yl!- (EP 157);and a TXA₂ antagonist, e.g., 5-heptenoic acid, 7- 3-2-(phenyl-amino)carbonyl!-hydrazino!methyl!7-oxabicyclo2.2.1!hept-2-yl!-, 1S 1α,2α(Z),3α,4α!!- (SQ 29548); benzenepropanoicacid, 2- 3-4 (pentylamino)carbonyl!-2-oxazolyl!-7-oxabicyclo2.2.1!hept-2-ylmethyl}- (BMS 180291); acetic acid, 4- 2-(phenylsulfonyl)amino!-ethyl!penoxy!- (sultroban, BM-13177);benzeneacetic acid, 4- 2- 4-chlorophenyl)sulfonyl!amino!ethyl!-(daltroban, BM-13505); (S-145 rac); 5-hexenoic acid, 6- 3-(4-bromophenyl)sulfonyl!amino!methyl!bicyclo 2.2.1)hep-2-yl!-, decylester, IS 1α2α2α(Z),- 3β,4α!!- (ONO 8809); 9H-carbazole-9-propanoicacid, 3- (4-fluorophenyl)sulfonyl!amino!-1,2,3,4-tetra-hydro-, (R)-(bay-u-3405); and (4Z)-6-(5S)-5-(4-chlor-phenylsulfonyl(aminomethyl)-cycloent-1-enyl!4-hexenoicacid (ZU 154343).

Examples of combinations of active agents which can be administeredconcurrently with a nitric oxide substrate and/or a nitric oxide donorand a progesterone (or other progestational agent) are low dose(e.g.,10-100 mg) of aspirin (or other cyclooxygenase inhibitor; PGI₂-mimetics (e.g., iloprost, cicaprost); combinations of a PGI₂ -mimeticand low dose aspirin.

Examples of dosage ranges of typical NO-substrates and NO-donors (peros) are:

    ______________________________________                 total dose:    ______________________________________    L-Arginine     500                mg-10 g p.o.    Sodium Nitroprusside                   range 500-2000     ug/kg/day    Nitroglycerin  0.5-10             mg    Isosorbid mononitrate                   10-100             mg    Isosorbid dinitrate                   10-100             mg    ______________________________________

The following are typical oral dosage ranges active agents of theprogestin and the optional other active agents concurrently administeredwith the nitric oxide substrate or donor:

Progestins: A daily dose bioequivalent to 50-300 mg of progesterone/day,e.g., an injectable suspension of medroxyprogersterone acetate toprovide a weekly dose of thereof of 100-1000 mg or tablets or drageesproviding an oral dose thereof of 5-10 mg/day; an injectable solution ofhydroxyprogesterone caproate which provides a weekly dose of 250-500 mg;tablets, capsules or dragees of northindrone acetate which provide adaily dose of 5-20 mg.

Cicaprost: 5-100 ug/kg/day p.o.

Aspirin: 10-100 mg/kg/day p.o.

The pharmacologically active agents employed in this invention can beadministered in admixture with conventional excipients, i.e.,pharmaceutically acceptable liquid, semi-liquid or solid organic orinorganic carriers suitable, e.g., for parental or enteral applicationand which do not deleteriously react with the active compound inadmixture therewith. Suitable pharmaceutically acceptable carriersinclude but are not limited to water, salt solutions, alcohols,vegetable oils, polyethylene glycols, gelatin, lactose, amylose,magnesium stearate, talc, silicic acid, viscous paraffin, perfume oil,fatty acid monoglycerides and diglycerides, pentaerythritol fatty acidesters, hydroxy methylcellulose, polyvinyl pyrrolidone, etc. Thepharmaceutical preparations can be sterilized and if desired mixed withauxiliary agents, e.g., lubricants, preservatives, stabilizers, wettingagents, emulsifiers, salts for influencing osmotic pressure, buffers,coloring, flavoring and/or aromatic substances and the like which do notdeleteriously react with the active compounds.

For parenteral application, particularly suitable are solutions,preferably oily or aqueous solutions, as well as suspensions, emulsions,or implants, including suppositories. Ampoules are convenient unitdosages.

In a preferred aspect, the composition of this invention is adapted foringestion.

For enteral application, particularly suitable are unit dosage forms,e.g., tablets, dragees or capsules having talc and/or a carbohydratecarrier or binder or the like, the carrier preferably being lactoseand/or corn starch and/or potato starch; particulate solids, e.g.,granules; and liquids and semi-liquids, e.g., syrups and elixirs or thelike, wherein a sweetened vehicle is employed. Sustained releasecompositions can be formulated including those wherein the activecompound is protected with differentially degradable coatings, e.g., bymicro-encapsulation, multiple coatings, etc.

Suitable for oral administration are, inter alia, tablets, dragees,capsules, pills, granules, suspensions and solutions. Each unit dose,e.g., each tablespoon of liquid or each tablet, or dragee contains, forexample, 5-5000 mg of each active agent.

Solutions for parenteral administration contain, for example, 0.01 -1%of each active agent in an aqueous or alcoholic solution.

The nitric oxide substrate and/or donor can be administered as anadmixture with the progestational agent and any other optional activeagent or as a separate unit dosage form, either simultaneouslythere-with or at different times during the day from each other.

The combination of active agents is preferably administered at leastonce daily (unless administered in a dosage form which delivers theactive agents continuously) and more preferably several times daily,e.g., in 2 to 6 divided doses. The typical dose is about 0.5 to 1000 mgof each active agent, although some less active agents, e.g.,L-Arginine, require much higher oral dosages, e.g., 500 to 10,000 mg,and others, e.g., sodium nitroprusside, require lower doses, e.g.,500-2,000 ug/kg/day. Doses for nitroglycerine typically are orally 2.5mg 2×daily; sublingually, 0.8 mg 1-4×daily; and transdermally, 0.2-0.4mg/hr. Since the LD₅₀ dosages of most of these active agents is known inthe prior art, a lower dosage regimen can be initiated and the dosageincreased until a positive effect is achieved or a higher dosage regimencan initially be employed, e.g., in a crisis situation, and the dosagesregulated downward as relief from the symptoms is achieved.

In humans, both L-arginine and progesterone (or bioequivalent of anotherprogestin) should be given in a ratio which produces blood plasma levelsof about 1-5 mMol/ml and 300-1,000 ng/ml (0.9-3 μMol/l), respectively.The NO-donor, e.g., sodium nitroprusside, should be given with theprogesterone (or bioequivalent of another progestin) in a ratioproducing blood plasma levels of about 1-10 μMol/l and 300-1,000 ng/ml(0.9-3 μMol/l), respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the drawings,

FIG. 1 is a series of strip chart recordings showing the effect ofL-arginine on spontaneously contracting uterine strips from rat on day18 of gestation;

FIG. 2: Dose-dependent relaxation effects of L-arginine (0.1 mM to 10mM) on spontaneously contracting uterine strips from rats at differentstages of gestation, during delivery and post partum. The tissues wereobtained on days 17-22 (d17, d18, d19 and d22) of gestation, on day 22(d22 del) during spontaeous delivery (1-3 pups delivered), or on 1(d1pp) and 2 (d2pp) days postpartum. The duration of complete inhibitionof spontaneous uterine contractions are dose-dependent. Data areanalyzed by repeated measures ANOVA on seven groups. The effects ofL-arginine from concentrations of 1 mM are significantly (P<0.01)decreased during spontaneous delivery at term and postpartum, comparedto all other times. Each data point represents mean ± S.E.M. The totalnumber of strips studied at each time period was 8-16 from 4-6 animalsper group.

FIG. 3: Dose response effects of L-arginine (0.6 mM to 10 mM) on thespontaeous contractility of uterine strips from ovariectomized adultrats. Animals received s.c. injection of 1 μg estradiol--17b (OVX+E), 2mg progesterone (OVX+P), estradiol and progesterone (OVZ+E+P) in sesameoil or oil alone (OVX+Oil) for 3 days prior to contractilitymeasurements. Values are mean ± SEM for 4 strips from each animal from 4rats per group. Data are analyzed by repeated measures ANOVA on fourgroups. *P<0.05 OVX+P vs OVX+E.

FIG. 4: 8-bromo-cGMP dose relaxation-response curves for uterine tissuesfrom rats delivering, spontaeously at term (DEL), preterm with ZK299(PRETERM DEL) and nondelivering (NONDEL) on day 18 of gestation. Eachpoint represents mean ± SEM for 4 strips from each animal from 4 ratsper group.

FIG. 5 is a bar chart which shows the effect on blood pressure of testanimals of 50 mg of the hypertensive agent L-NAME, alone or incombination with one or both of L-arginine and progesterone (R-5020);and

FIG. 6 is bar chart which shows the effect in the same experiments onpup weights of these compounds.

DISCUSSION OF THE DRAWINGS

The strip chart recordings of FIG. 1 show that the application ofL-arginine (1-3 mM) (A, B, E), sodium nitroprusside (5 mM)(C), nitricoxide (0.1 mM) (D) to muscle baths produced substantial relaxations. Theeffects of L-arginine were reversed by L-NAME (3 mM)(B) and methyleneblue (0. mM)(E). These are typical recordings of 8-16 strips from 6animals in each group. Each upstroke from baseline represents acontraction.

The strip chart recording of FIG. 1C shows that the application ofsodium nitroprusside (SNP) caused sustained relaxation in spontaneouslycontracting uterine strips after a lag period and that tissues in therelaxed state were responsive to potassium chloride. Similar recordingsof 12 uterine strips from 4 animals were obtained.

The strip chart recording in FIG. 1D shows the relaxation produced byauthentic nitric oxide gas (0.1 mM). Similar recordings were obtainedfrom 8 strips from 4 animals.

The strip chart recordings of FIG. 1E show that L-arginine (1 mM)produced relaxation of spontaneously contracting tissues and theseeffects were repeatable in the same strip (as in FIG. 1A) and that therelaxation effect of L-arginine (1 mM) was abolished by methylene blue(0.1 mM) when added before the application of L-arginine (B).

In the experiments whose results are shown by the graph of FIG. 2, thetissues were obtained on days 17-22 (d17, d18, d19 and d22) ofgestation, on day 22 (d22 del) during spontaneous delivery (1-3 pupsdelivered), or on 1 (d1pp) and 2 (d2pp) days postpartum. The duration ofcomplete inhibition of spontaneous uterine contractions aredose-dependent. The effects of L-arginine from concentrations of 1 mMare significantly (P<0.01) decreased during spontaneous delivery at termand postpartum, compared to all other times. Each data point representsmean ± S.E.M. The total number of strips studied at each time period was8-16 from 4-6 animals per group.

In the experiments whose results are shown by the graph of FIG. 3,nonpregnant ovariectomized rats received s.c. injection of 1 μgestradiol-17-β (OVX+E), 2 mg progesterone (OVX+P), estradiol andprogesterone (OVX+E+P) in sesame oil or oil alone (OVX+Oil) for 3 daysprior to contractility measurements. Values are mean ± SEM for 4 stripsfrom each animal from 4 rats per group. *P<0.05 OVX+P vs OVX+E.

The charge of FIG. 4 shows 8-bromo-cGMP dose relaxation-response curvesfor uterine tissues from rats delivering, spontaneously at term (DEL),preterm with ZK299 (PRETERM DEL) and nondelivering (NONDEL) on day 18 ofgestation. Each point represents mean ± SEM for 4 strips from eachanimal from 4 rats per group.

The data in Table 1 below show the effects of L-NAME infusion on bloodpressure (mm Hg) in pregnant rats.

                  TABLE 1    ______________________________________    Blood Pressure (mm Hg)                      L-NAME    Gestation day               CONTROL      25 mg/day                                     50 mg/day    ______________________________________    Day 15     121 ± 3.sup.a                            119 ± 2.sup.a                                     123 ± 3.sup.a    Day 18     119 ± 3.sup.a                            144 ± 4.sup.b                                     166 ± 2.sup.c    Day 22     120 ± 5.sup.a                            146 ± 2.sup.b                                     168 ± 3.sup.c    ______________________________________

Means with different superscripts differ significantly (P<0.05)

The data in Table 2 below show the delivery and the pups delivered ofL-NAME infusion to pregnant rats.

                  TABLE 2    ______________________________________                     L-NAME              CONTROL  25 mg/day  50 mg/day    ______________________________________    Day of Delivery                22.3 ± 0.2                           22.4 ± 0.2                                      22.7 ± 0.2    Total # of pups                59         65         56    # of dead pups                2          5          10    Weight of pups                6.32 ± 0.05.sup.a                           5.05 ± 0.08.sup.b                                      4.56 ± 0.10.sup.c    Total # of animals                8          9          10    ______________________________________

Means with different superscripts differ significantly (P<0.05).

Another experiment using L-NAME-induced" preeclampsia" showed thattreatment with L-arginine alone partially reduced blood pressure (FIG.5). Similarly, animals treated with L-NAME and R 5020 (promegestone), aprogestational agent with no antimineralocorticoid effect or otherantagonistic or agonistic properties, also partially reducedL-NAME-induced hypertension. As also shown in FIG. 5, when the samedoses of L-arginine and R 5020 were given simultaneously, their combinedeffect lowered blood pressure to normal levels.

Additionally, evaluation of fetal weights in the same animals treated asdescribed above, showed intrauterine fetal retardation (decreased weightof pups), typical preeclamptic fetuses (FIG. 6). Treatment of the"preeclamptic" groups of animals with either L-arginine alone or R 5020alone slightly but statistically significant, elevated fetal weights. Asalso shown in FIG. 6, the combined effect of the two compoundsadministered together significantly elevated fetal weight above thatobserved with either compound alone, a highly significant advantage tosurvival of the fetus under these conditions.

It can be concluded from these studies that the combined treatment ofL-arginine with a progestational agent whose activity is "pure", like R5020 provides results which cannot be achieved with either type of drugalone. The studies show that the basis for this effectiveness lies inthe ability of the progestional agent to increase the effectiveness ofnitric oxide (or L-arginine, the substrate of nitric oxide) to dilatebood vessels and thereby lower blood pressure as well as increasefetalmaternal profusion, thereby increasing fetal weight.

The combined effect of the combination of these agents is surprisinglydramatic and, more importantly, the significant fetal and maternaleffects observed with treatment with the combination. Prior medicalevidence does not suggest that the combination would provide theseadvantages, because the basis for them is not the simple combination oftwo agonistic compounds but instead is the sensitizing of nitric oxideprovided by the progestin. The studies clearly indicate that progestinsincrease the effector system for nitric oxide (not increase nitric oxidesynthesis).

The method of treatment employed in this invention can also be employedfor the treatment of hypertension (in both females and males),climacteric disorders (hot flashes, mood swings) in menopausal women,thrombotic disorders, menstrual disorders (dysmenorrhea, functionaluterine bleeding), and hemorrhage, etc., following the dosage regimedescribed herein.

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The preferred specific embodiments are, therefore,to be construed as merely illustrative, and not limitative of thedisclosure in any way whatsoever.

The entire disclosure of all applications, patents and publications,cited above and below are hereby incorporated by reference.

EXAMPLES Example 1 Treatment of Preeclampsia

To a pregnant human female (ca 20-40 years; 60-80 kg) usually in hersecond half of pregnancy and displaying the symptoms of preeclampsia,including hypertension (above 140 mm systolic and above 90 mmdiastolic), edema and protein-uria, administer 0.5 to 20 g of L-arginineand 200 mg of micronized progesterone per os daily in three divideddoses until the symptoms are ameliorated. Thereafter, administer 0.5 to5 mg of L-arginine and 60 mg of progesterone per os daily whenever thediastolic pressure rises above 80 mm; with increasing doses ofL-argininine to from 5 to 20 mg daily until remission of the symptomsagain occurs.

Example 2 Treatment of preeclampsia

To a human female comparable to and displaying the same symptoms as theone described in Example 1, administer daily 2×2.5 mg of nitroglycerineand 200 mg of progesterone following the same protocol, until thesymptoms are ameliorated.

Example 3 Treatment of Preterm Labor

To a human female in her sixth month of pregnancy and displayingsymptoms of a threatened spontaneous abortion, including blood spottingand periodic uterine spasms, administer daily 17 g of L-arginine and 50mg of progesterone per os daily in three divided doses until thesymptoms are ameliorated. Thereafter, administer 5 g of L-arginine and50 mg of progesterone per os daily with increasing doses to 20 g ofL-arigine daily until remission of the symptoms again occurs.

Example 5 Treatment of Preterm Labor

To a pregnant human female comparable to and displaying the samesymptoms as the one described in Example 3, administer daily 2×25 mg ofnitroglycerine and up to 180 mg of progesterone, following the sameprotocol, until the symptoms are ameliorated.

The preceding examples can be repeated with similar success bysubstituting the generically or specifically described reactants and/oroperating conditions of this invention for those used in the precedingexamples.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention, and withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

What is claimed is:
 1. A method of treating preeclampsia accompanied orunaccompanied by preterm labor in a pregnant female mammal, whichcomprises administering to a female in need of such treatment(a) aneffective amount of a progestin; and (b) an effective amount of nitricoxide synthase substrate, an effective amount of a nitric oxide donor,or both; andoptionally, further comprising administering effectiveamounts of one or more agents selected from the group consisting of acyclooxygenase inhibitor, a PGI₂ -mimetic, a thromboxane (TXA₂)inhibitor, a compound possessing PGI₂ -agonistic and TXA₂ -inhibitingproperties, a compound possessing TXA₂ -antagonistic and PGI₂ -mimeticactivities, and a TXA₂ -antagonist.
 2. The method of claim 1, whereinthe female mammal is a human suffering from preeclampsia unaccompaniedby preterm labor.
 3. The method of claim 1, wherein the female mammal isa human also exhibiting symptoms of preterm labor.
 4. The method ofclaim 1, wherein the female mammal is a human and a nitric oxidesynthase substrate is administered thereto.
 5. The method of claim 4,wherein the substrate is L-arginine.
 6. The method of claim 1, whereinthe female mammal is a human and a nitric oxide donor is administeredthereto.
 7. The method of claim 6, wherein the nitric oxide donor issodium nitroprusside, nitroglycerin, glyceryltrinitrate, SIN-1,isosorbidmononitrate or isosorbiddinitrate.
 8. The method of claim 6,wherein the nitric oxide donor is administered orally.
 9. The method ofclaim 1, wherein the female mammal is a human and the nitric oxidesubstrate or donor is administered thereto in combination with acyclooxygenase inhibitor.
 10. The method of claim 9, wherein theinhibitor is aspirin.
 11. The method of claim 1, wherein the femalemammal is a human and the nitric oxide substrate or donor isadministered thereto in combination with a PGI₂ -mimetic.
 12. The methodof claim 11, wherein the PGI₂ -mimetic is iloprost or cicaprost.
 13. Themethod of claim 1, wherein the female mammal is a human and theprogestin administered thereto is progesterone.
 14. A method of treatingpreeclampsia accompanied or unaccompanied by preterm labor in a pregnantfemale mammal comprising administering an effective amount of a nitricoxide synthase substrate, a nitric oxide donor or both.
 15. A method ofclaim 14, comprising administering a nitric oxide synthase substrate.16. A method of claim 15, wherein the substrate is L-arginine.
 17. Amethod of claim 14, wherein the female is a human.
 18. A method of claim14, wherein a nitric oxide donor is administered.
 19. A method of claim18, wherein the nitric oxide donor is sodium nitroprusside,nitroglycerin, glyceryltrinitrate, SIN-1, isosorbidmononitrate orisosorbiddinitrate.
 20. A method of claim 14, wherein the synthasesubstrate or donor is administered orally.
 21. A method of claim 15,wherein the amount of nitric oxide synthase substrate is effective toraise the blood level of circulating L-arginine to at least about 1mmole above the normal circulating level of L-arginine.
 22. A method ofclaim 18, wherein the amount of nitric oxide donor is effective toprovide a blood level of such donor of about 1-1000 nmole.